Device for magnetically regulating each stop position of an intermittently rotating output member

ABSTRACT

An intermittently rotating indexing wheel is provided with a stop-position regulating device for regulating each successive stop position of the indexing wheel. The stop-position regulating device comprises a toothed wheel composed of magnetic material attached to the indexing wheel and a pair of magnetic members positioned in opposed relationship to the toothed wheel and suitably spaced-apart from each other a distance equal to a whole number multiple of the distance between two teeth on the toothed wheel. A permanent magnet is coupled to the pair of magnetic members and a magnetic circuit is established which includes the pair of magnetic members and the toothed wheel whereby each successive stop position of the toothed wheel and therefore that of the indexing wheel is precisely regulated.

United States Patent 1191 1111 3,719,839 Endo [451 March 6, 1973 [541DEVICE FOR MAGNETICALLY 2,834,896 5/1958 Fisher ..310 49 REGULATING EACHSTOP POSITION 3,596,119 7/1971 Goldmann ..310/49 OF AN INTERMITTENTLYROTATING OUTPUT MEMBER lnventor: Yukio Endo, Matsudo, Japan Assignee:Kabushiki Kaisha Hattori Tokeitena,

Tokyo, Japan March 23, 1971 Filed:

Appl. No.:

Foreign Application Priority Data March 25, 1970 Japan 45/27866References Cited UNITED STATES PATENTS Primary Examiner-D. F. DugganAttorney--Robert E. Burns and Emmanuel J. Lobato ABSTRACT Anintermittently rotating indexing wheel is provided with a stop-positionregulating device for regulating each successive stop position of theindexing wheel. The stop-position regulating device comprises a toothedwheel composed of magnetic material attached to the indexing wheel and apair of magnetic members positioned in opposed relationship to thetoothed .wheel and suitably spaced-apart from each other a distanceequal to a whole number multiple of 1 5 Claims, 2 Drawing Figures DEVICEFOR MAGNETICALLY REGULATING EACH STOP POSITION OF AN INTERMITTENTLYROTATING OUTPUT MEMBER The present invention relates to stopposition-regulating means for timepieces wherein an intermittent rotaryindexing wheel may be precisely stopped at a predetermined positionafter each incremental movement.

In the conventional stop position-regulating means for intermittentrotary indexing wheels of a timepiece, there is provided an indexingwheel composed of magnetic material and a permanent magnet arranged inopposition to the toothed portion of the indexing wheel so that theindexing wheel may be magnetically regulated at its stop position whereany one tooth on the indexing wheel is brought into opposed alignmentwith the permanent magnet.

The conventional technique as above described,

however, is disadvantageous since the magnetic path is I left opened andthe magnetic flux therefore leaks out of the magnetic path with thedetrimental result that a feeble magnetic force is provided toaccomplish the regulation. Moreover, the permanent magnet employed insuch systems is subjected to deterioration due to aging.

The present invention is intended to provide a novel and improved stopposition regulating means for an intermittent rotary wheel whichovercomes the above disadvantages.

In accordance with the present invention, there is provided an improvedmeans for magnetically regulating the stop position of an intermittentrotary wheel comprising an intermittent rotary wheel made of magneticmaterial, two members arranged in adjacent opposition to theintermittent rotary wheel and spaced apart from one another, aconnecting plate interconnecting the two members with each other, andwherein at leastany one of either the connecting plate or one of the twomembers is a permanent magnet.

Thus, a closed magnetic path having two narrow spaces existing betweenthe intermittent rotary wheel and the two members is provided wherebythe intermittent rotary wheel may be positively and precisely stopped ata predetermined position after each angular displacement of the wheel.Therefore, the intermittent rotary wheel is effectively prevented fromundergoing excessive angular motion which may be otherwise caused by theinertia force of the wheel itself.

One object of the present invention is therefore to provide an improvedstop position-regulating means for an intermittent rotary wheel whichhas a high degree of regulating accuracy and which is hardly subjectedto any aging deterioration.

Other objects and characteristic features of the present invention willbecome evident and will be more readily understood by the followingdescription and claims taken inconjunction with the accompanyingdrawings, in which:

FIG. 1 is a plan view illustrating one embodiment of the presentinvention; and

F IG. 2 is an enlarged perspective view, partly in cross-section, of theembodiment shown in FIG. 1.

Referring now to FIGS. 1 and 2, a balance device 1 comprises two balancewheels 3 and 4 mounted upon a rotatable balance staff 2. The balancestaff 2 is provided with a balance screw 5 for selectively adjusting theaxial position of the balance staff 2. In order to drive the balancedevice 1 in a reciprocating oscillatory manner, conventional magneticdriving means is employed and comprises a pair of magnets 6 and 7secured in opposition to each other on the respective balance wheels 3and 4. A pick-up and driving coil 8 is mounted on a support plate 9 andis disposed between the magnets 6 and 7 and coacts therewith toelectromagnetically oscillate the balance staff 2. The electriccircuitry for actuating the magnetic driving means has been omitted inthe accompanying drawing and such circuitry is well-known in the art. Abalancing mass 10 is secured to the balance wheel 3 and other balancingmass 11 is secured to the balance wheel 4 and these balancing masses aredisposed in opposition to the respective magnets 6 and 7 to effectivelybalance the balance wheels.

An indexing wheel arbor 14 is rotatably journalled between an upperplate 12 and a middle plate 13 and .has secured thereon a crown-shapedindexing wheel 15 and an indexing wheel pinion 16. The indexing wheel 15is provided with a series of circumferentially spacedapart dependingprojections 15' and the pinion 16 is provided with a set of gear teeth.

The balance staff 2 is further provided with a drive plate 17 engageablewith the projections 15' to effect intermittent rotation of the indexingwheel 15 in response to oscillation of the balance staff 2. The indexingwheel 15 has coaxially mounted thereon a lock wheel 18 which is providedon the periphery thereof with a series of circumferentially spaced-apartteeth or radially extending projections T T T The lock wheel 18 iscomposed of a material, preferably paralloy, which has a high magneticpermeability.

Two elongated magnets 19 and 20 are press fitted in I apertures locatedin the middle plate 13. In the embodiment disclosed, the magnets 19 and20 are cunife or vicalloy magnets. The magnets 19 and 20 may also bemade of ferrite, however in this instance, the magnets should be affixedto the middle plate 13 by means of a bonding material. The lower endportions of the magnets 19 and 20 are connected to a plate magnet 21which is attached to the middle plate 13.

The elongated magnets 19 and 20 and the plate magnet are initiallymagnetized in the following manner. The magnetizable members 19, 20 and21 are first arranged, as shown in the drawings, on the middle plate 13and a conductive wire is then introduced between the members 19 and 20.Then a plate having a high magnetic permeability is placed atop themagnetizable members 19 and 20 whereby the conductive wire is enclosedby the magnetizable members 19, 20 and 21 and the plate having a highmagnetic permeability.

Then a strong electric current pulse is fed through the conductive wire,thereby momentarily creating a strong magnetic field around theconductive wire. The magnetizable members 19, 20 and 21 are influencedby the strong magnetic field and are accordingly strongly magnetized.Subsequently, the plate of high magnetic permeability and the conductivewire are both removed and then the indexing wheel 15 and the other gearwheels are mounted on the middle plate 13 to form a gear-train.

The elongated magnets 19 and 20 are each arranged such that their endfaces situated at their respective upper extremities lie in a commonplane and are opposed to the path of travel of the teeth of the lockwheel 18 with a narrow space therebetween. The magnets 19 and 20 aresuitably spaced-apart from each other and occupy a relative positionalrelationship such that when one of the magnets is opposed in alignedsuperposition to one tooth of the lock wheel 18, the other magnet issimilarly opposed in aligned superposition to another tooth of the lockwheel.

The operation of the stop position-regulating means having the structureas described above will now be described.

The balance device 1 is driven in a well known manner by the magneticdriving means to undergo a reciprocating oscillatory movement as shownby the arrows in FIG. 1, through a predetermined angular range.

The drive plate 17 secured on the balance staff 2 coacts with theindexing wheel 15 to intermittently rotate same in the direction of thearrow shown in FIG. 2. Accordingly, the lock wheel 18 coaxially mountedon the indexing wheel 15 is also intermittently rotated in the samedirection.

In the position shown in FIG. 2, the two teeth T and T of the lock wheel18 are respectively positioned alignment in opposition to the magnets 19and 20. In this position, the magnets 19, 20 and 21 and the lock wheel18 constitute a closed magnetic path including as a part thereof the twonarrow air spaces existing between the magnets 19 and 20 and therespective teeth T and T of the lock wheel 18. Accordingly, the magneticflux density between the magnets 19 and 20 and the lock wheel 18 is highand the lock wheel 18 is subjected to a powerful attractive force by themagnets 19 and 20 thereby ensuring that the lock wheel 18 preciselystops at its predetermined position.

Reciprocating rotational movement of the balance device 1 then causesthe lock wheel 18 to angularly rotate through one pitch thereof in thedirection of the arrow shown in FIG. 2 until the teeth T, and T of thelock wheel 18 move to the position where they are respectively opposedto and aligned with the magnets 19 and 20. In this position of the lockwheel 18, the closed magnetic path is again established by thecombination of the magnets 19, 20 and 21 with the lock wheel 18 and thelock wheel 18 is precisely stopped at its predetermined position.

Any time the lock wheel 18 tends to stop in a position other than one ofits predetermined positions, the magnetic flux path of the magneticcircuit is accordingly lengthened due to an increased in length of thetwo air gaps. Under such conditions, an attractive force is exerted onthe movable lock wheel 18 tending to move and position same such thattwo teeth T are aligned with respective ones of the magnets 19 and 20.Thus it will be understood that the lock wheel 18 is accurately stoppedafter each intermittent angular displacement of the indexing wheel bythe regulating effect of the magnets 19 and cooperating with the toothedlock wheel 18. When the indexing wheel 15 arrives at one of itspredetermined stop positions, two teeth T of the lock wheel 18 are inaligned opposition to the magnets 19 and 20 and the magnetic path isthen effectively closed.

It is not absolutely necessary to make all the magnetizable members 19,20 and 21 into permanent magnets, as in the above-described embodiment,and it is sufficient to make at least one of these members a permanentmagnet.

It is preferable in the present invention that the middle plate 13 becomposed of a non-magnetic material, such as aluminum or the like, tomore effectively suppress the magnetic flux leakage from the magnets 19and 20 and the connecting plate 21.

Although a toothed lock wheel 18 is employed in the embodiment disclosedherein, a disc-shaped lock wheel may be used instead. In this alternateembodiment, the lock wheel is continuously subjected to the attractiveforce of the magnets 19 and 20 with the attendant result that a brakingforce always exists whereby the lock wheel is accurately stopped at itspredetermined position and prevented from undergoing excess rotation dueto its own inertia. Thus, the rotary wheel is effectively regulated tomake intermittent rotation with extreme accuracy.

What I claim and desire to secure by Letters Patent is:

1. A device for magnetically regulating the stop positions of anintermittently rotating output member comprising: an intermittently androtationally driven output member; a lock wheel connected to andintermittently rotated by said output member and having a circularperipheral portion composed of a plurality of circumferentially andequidistantly spaced-apart radially extending magnetic projections; andstop-position regulating means coacting with said lock wheel formagnetically regulating each successive stop position of theintermittently rotated output member comprising a pair of spaced-apartmagnetic members each having at least one planar end face, meanspositioning said pair of magnetic members a distance apart correspondingto a whole number multiple of the distance between two successivemagnetic projections and positioning said magnetic members so that oneplanar end of each magnetic member lies in a common plane and lies insuperposed alignment with successive ones of said magnetic projectionsduring intermittent rotation of said lock wheel, means including saidpair of magnetic members and said circular peripheral portion of saidlock wheel defining a magnetic path having minimum reluctance whenevertwo of said magnetic projections simultaneously directly align insuperposition with said pair of magnetic members, and means establishinga magnetic flux in said magnetic path effective to precisely stop saidlock wheel in successive stop positions defined by the simultaneousaligned superposition of the two magnetic projections with said pair ofmagnetic members to thereby effect precise stopping of saidintermittently rotated output member in each successive stop position.

2. A device according to claim 1; wherein said means defining a magneticpath includes a magnetic plate member interconnecting said pair ofmagnetic members.

3. A device according to claim 2; wherein said means establishing amagnetic flux comprises a permanent magnet constituting at least one ofsaid magnetic members.

4. A device according to claim 2; including a support plate composed ofnon-magnetic material, and means mounting said pair of magnetic membersand said magnetic plate member on said support plate.

5. A device according to claim 1; wherein said output member comprises abalance staff; and means including an indexing wheel concentricallyaffixed to said lock wheel for effecting intermittent rotation of saidlock wheel in response to intermittent rotation of said 5 balance staff.

1. A device for magnetically regulating the stop positions of anintermittently rotating output member comprising: an intermittently androtationally driven output member; a lock wheel connected to andintermittently rotated by said output member and having a circularperipheral portion composed of a plurality of circumferentially andequidistantly spaced-apart radially extending magnetic projections; andstop-position regulating means coacting with said lock wheel formagnetically regulating each successive stop position of theintermittently rotated output member comprising a pair of spaced-apartmagnetic members each having at least one planar end face, meanspositioning said pair of magnetic members a distance apart correspondingto a whole number multiple of the distance between two successivemagnetic projections and positioning said magnetic members so that oneplanar end of each magnetic member lies in a common plane and lies insuperposed alignment with successive ones of said magnetic projectionsduring intermittent rotation of said lock wheel, means including saidpair of magnetic members and said circular peripheral portion of saidlock wheel defining a magnetic path having minimum reluctance whenevertwo of said magnetic projections simultaneously directly align insuperposition with said pair of magnetic members, and means establishinga magnetic flux in said magnetic path effective to precisely stop saidlock wheel in successive stop positions defined by the simultaneousaligned superposition of the two magnetic projections with said pair ofmagnetic members to thereby effect precise stopping of saidintermittently rotated output member in each successive stopposition.
 1. A device for magnetically regulating the stop positions ofan intermittently rotating output member comprising: an intermittentlyand rotationally driven output member; a lock wheel connected to andintermittently rotated by said output member and having a circularperipheral portion composed of a plurality of circumferentially andequidistantly spaced-apart radially extending magnetic projections; andstop-position regulating means coacting with said lock wheel formagnetically regulating each successive stop position of theintermittently rotated output member comprising a pair of spaced-apartmagnetic members each having at least one planar end face, meanspositioning said pair of magnetic members a distance apart correspondingto a whole number multiple of the distance between two successivemagnetic projections and positioning said magnetic members so that oneplanar end of each magnetic member lies in a common plane and lies insuperposed alignment with successive ones of said magnetic projectionsduring intermittent rotation of said lock wheel, means including saidpair of magnetic members and said circular peripheral portion of saidlock wheel defining a magnetic path having minimum reluctance whenevertwo of said magnetic projections simultaneously directly align insuperposition with said pair of magnetic members, and means establishinga magnetic flux in said magnetic path effective to precisely stop saidlock wheel in successive stop positions defined by the simultaneousaligned superposition of the two magnetic projections with said pair ofmagnetic members to thereby effect precise stopping of saidintermittently rotated output member in each successive stop position.2. A device according to claim 1; wherein said means defining a magneticpath includes a magnetic plate member interconnecting said pair ofmagnetic members.
 3. A device according to claim 2; wherein said meansestablishing a magnetic flux comprises a permanent magnet constitutingat least one of said magnetic members.
 4. A device according to claim 2;including a support plate composed of non-magnetic material, and meansmounting said pair of magnetic members and said magnetic plate member onsaid support plate.